Dengue epidemiology& case management

dengue fever, epidemiology, aedes, mosquito, vector competence, vector capacity, vector, treatment, case management, diagnosis, DHF, DSS, DF, DENV, arbovirus

1. Epidemiology of Dengue Dr Menaal K. JR- II Department of S. p. m s. n. medical college, agra

2. The Epidemiological Triad

3. The Agent Arbovirus ( ss RNA Virus) Genus F lavivirus Family Flaviviraede 4 serotypes- DENV 1, DENV 2, DENV 3& DENV 4 Micro evolution : Many virulent genotypes are evolving to replace non virulent genotypes Antigenic similarity but infection with one serotype does not provide lifelong immunity for other serotypes ( Cross Immunity lasts only a few months), … I nstead prior immune sensitization worsens the disease scenario

4. Denv Has… A lipoprotein envelope 3 structural protein genes encoding: {CME} Nucleocapsid or core protein (C), M embrane- associated protein (M), E nvelope protein (E), and 7 non-structural protein (NS) genes i ncluding, envelope glycoprotein, NS 1 NS 1 is of diagnostic and pathological importance. It is associated with viral haemagglutination and neutralization activity.

5. The Host Infective Stage: 1 day before onset of fever to day 5 Intrinsic Incubation Period: 4- 6 days High Risk Patients: Extremes of Age Pregnancy Any condition prone to heavy blood loss: Peptic ulcer disease; menstruation; haemolytic anaemia; G- 6PD deficiencies ; thalassemia; patients on steroids, NSAIDS Any chronic condition: DM, HTn, Asthma, Cirrhosis, IHD, CRF

6. Remember… “Prior immune sensitization worsens the disease scenario” 1 st Infection with DENV- 1 Asymptomatic/ Non specific manifestations/ DF 2nd Infection with DENV- 2, 3 or 4 DHF/ DSS/ Severe Disease Secondary Infection with DENV 2 or multiple infections with different serotypes causes Severe Disease (DHF/ DSS) DENV 1/ DENV 2 Sequence is the worst

7. Non neutralizing Ab (s) Mononuclear cells Cytokines, vasoactive mediators procoagulants DIC 2 nd Infection

8. The Amplifiers Man Monkey

9. The Transmission Cycles Enzootic Monkey- Aedes - Monkey- Aedes Epizootic From Epidemic Cycle, DENV Crosses Over To Non Humans Via Bridge Vectors, esply Macaca s inica In Sri Lanka Epidemic Human- Aedes - Human- A edes

10. Humans Mosquito Humans Extrinsic I P Mosquito Intrinsic I P= 4- 6 days (Range: 3- 14 days) Extrinsic I P= 8- 10 days Intrinsic I P

11. The Environment Tropical& Sub- tropical Urban, P eri urban; Rural Rapid Unplanned uncontrolled urbanization , Transportation : human movement and congregation Consumerism- Non biodegradable plastic, mismanaged solid waste disposal Poor water storage and management Seasonal Pattern: Post Monsoon (But Perennial in Gujarat& South India)

12. When you see these sights, know for sure… You have invited dengue… its near!!

13. An Epidemic, Endemic& Hyper Endemic South- East Asia is divided into 3 Categories: Cat A: India, Bangladesh, Myanmar, Sri Lanka, Indonesia, Thailand, Maldives Cat B: Bhutan, Nepal Cat C: DPR Korea

14. Global Warming 2 degree rise in temp- Shortens extrinsic IP- more infected mosquitos to further spread DENV Enhances the life cycle of A edes Shortens the size of the mosquito Rise in temp- mosquito bites more frequently due to “dehydration”- further spreads DENV

15. The Vector Ae a lbopictus Eggs Survive Sub Freezing Temp Ae aegypti - Cosmo tropical species between latitudes 45°N and 35°S Vector Competency Vector Capacity Transovarial Spread Endophagic , Endophilic 16- 35 °C, 60- 80% Relative Humidity

16. Vector Competency High susceptibility to infecting virus Ability to replicate the virus Ability to transmit the virus to another host Both A e . a egypti and A e . a lbopictus carry high vectorial competency for dengue viruses.

17. Vectorial C apacity : Depends on the Environmental and Biological characteristics of the Vector Ae . aegypti Highly domesticated S trongly anthropophilic N ervous feeder (i.e. it bites more than one host to complete one blood meal) and D iscordant species (i.e. it needs more than one feed for the completion of the gonotropic cycle ) These habits epidemiologically result in the generation of multiple cases and the clustering of dengue cases in cities. Ae . albopictus Feral F eeds on both humans and animals A ggressive feeder ( i.e. it can complete its blood meal in one go on one person) C oncordant species (does not require a second blood meal for the completion of the gonotropic cycle ) So, Ae . albopictus has poor vectorial capacity.

18. Distribution of Aedes aegypti

19. Distribution of Aedes albopictus

20. The Spectrum 2- 5% cases

21. Undifferentiated Fever Primary dengue infection May develop a simple fever indistinguishable from other viral infections. Maculopapular or rubelliform rashes on face, neck and chest may accompany the fever or may appear during defervescence (Day 3-5) URTI and GI symptoms are common

22. Dengue Fever Older children, adolescents and adults Acute (Sudden, sharp) rise in temperature (39 °C - 40°C) for 5- 7 days Biphasic fever with severe headache, myalgia, arthralgia and bone pains ( break-bone fever ), particularly in adults Rashes, flushed face, retro-orbital pain on eye movement or eye pressure, photophobia Altered taste sensation, Anorexia, Sore throat, Dragging pain in inguinal region Leukopenia and thrombocytopenia- mild Occasionally, Haemorrhage such as gastrointestinal bleeding, hyper menorrhea, massive epistaxis (DF with Hmrgh )

23. Sub conjunctival Haemorrhage Petechial Haemorrhages Pale islands in the red sea Maculo- papular Rash

24. Dengue Haemorrhagic Fever (DHF) Children less than 15 years of age in hyper endemic areas , in association with repeated dengue infections (secondary dengue infection). Incidence of DHF in adults is increasing Rarely DHF may occur in Primary infections with DENV-1 and DENV-3 as well as in infants . Signs and symptoms similar to DF in the early febrile phase. Pale islands in red sea P ositive tourniquet test (TT) , petechiae on extremities, easy bruising and/or GI haemorrhage Abnormal haemostasis and plasma leakage are the main pathophysiological hallmarks of DHF Thrombocytopenia and rising haematocrit / haemo concentration before the subsidence of fever/ onset of shock.

25. Warning Signs That May Occur At Or After Defervescence (The Presence Of One Or More Of These Signs Indicates The Need For Immediate Medical Evaluation): Abdominal pain or tenderness Persistent vomiting Clinical fluid accumulation (i.e., Pleural effusion or ascites) Mucosal bleeding Lethargy or irritability, restlessness Oliguria Postural Hypotension Liver enlargement (≥2cm) Increases in haematocrit concurrent with rapid decrease in platelet count

26. Dengue Shock Syndrome (DSS) Hypovolemic shock due to plasma leakage Pleural effusion, Ascites (plasma leakage to pleural& peritoneal cavities) Hypothermia- Cold clammy skin I C Bleeding Fulminant hepatic failure Optimal fluid management is important- Avoid over hydration

27. DSS Is of short duration (12- 24 hrs ), But can be fatal Patient is conscious till stage 4 of the shock (BP not recordable) Usually SBP falls late, but pulse pressure (SBP-DBP) deteriorates much earlier ≤ 20 mmHg If prolonged, Shock causes metabolic acidosis and multi organ failure

28. Expanded Dengue Syndrome Severe organ involvement such as liver, kidneys, brain or heart +/- evidence of plasma leakage May be associated with co- infections, comorbidities or complications of prolonged shock

29. Depression, Bradycardia Asthenia Circumoral cyanosis, weak thread pulse

30. The Management

31. Early Diagnosis

32. Case Management During an epidemic, every hospital should have Dengue Triage Facility. High risk Cases should be screened in the special Dengue OPD, on the basis of history of any bleeding episodes, presence of warning signs, spread of dengue infection in the neighbourhood along with fever. All these cases should be lab investigated On confirmation they need to be observed and managed in a Special Dengue Wards All dengue cases must be notified as soon as possible

33. Management of Dengue Cases Fluid Intake- Oral or IV. ORS and fruit juices Better than water Antipyretics- PCM. AVOID ASPIRIN (May cause Rye’s Syndrome); other NSAIDS , e.g. IBUPROFEN (these may cause gastric bleeding) Monitor for warning signs Daily check PCV from Day 3 of fever till Day 2 after fever

34. Indications of Red Cell Transfusion Loss of blood (Overt blood loss)- 10% or more of total blood volume - give whole blood Refractory shock despite adequate fluid administration and declining PCV Replacement Volume should be 10ml/ kg Coagulogram should be done If fluid overload happens, give packed cells

35. Indication of Platelet Transfusion There is no need to give prophylactic platelets even at <20, 000/ cumm Prophylactic platelets should be given at levels <10 , 000 / cumm Prolonged shock with coagulopathy and abnormal coagulogram If systemic massive bleeding , platelet transfusion may be needed in addition to red cell transfusion

36. Criteria for Discharge of the Patient Absence of fever for >24hr (without the use of antipyretics) Return of appetite Good urine output Visible clinical improvement Minimum 2- 3 days after recovery from shock No respiratory distress (due to pleural effusion or ascites) Platelet count > 50, 000/ cumm